414 Journal of the Asiatic Society of Bengal. [NS., XI, 
sediments of the rivers which drained the highlands to the 
north and east, and probably had an opening only towards 
the south. I shall proceed to show that it must have beena 
continually subsiding area. until late tertiary times, while the 
barrier ‘of the Arakan Yoma formed an ever rising geoanticline. 
It is important to observe that subsidence and not upheaval 
has prevailed in the Irrawaddy Basin during the greater part 
of the tertiary era. As time went on, the head of the gulf 
filled up, and became land, while the sea retreat+d to the south. 
The fluviatile sediments and deltaic deposits kept continually 
shifting southwards in step with this retreat. The area of 
subsidence also has apparently shifted to the south, and i 
is not at all improbable that the present Gulf of Martaban 
forms a subsiding geosynelinal area. Subsidence ea” 
the 
turn. 
ormed a continually rising Geoanticline.—Conglo- 
merates, indicating the proximity of a coast-line, are of frequen’ 
: t, while the 
formation. 
In the Minbu district conglomerates are common in the Hes 
To the south of Minbu, the Irrawaddy series on north 
of the district. lf, however, we wish to obiain good o furthet } 
of marine fossils from the upper Pegus, we must g0 still 4 
ve such forma 
{4 
tions as the Kama Clay,—a formation which 1s represent a 
as Myaing in the north of the district: that 
deltaic conditions with frequent emergence © 
akokku district, but excepting the south-eas 
(Yenangyat, Shinmataung), that these deltaic ©° 
tended also in P times to the north-west quar et 
Minbu district (area north of Ngahlaingdwin)._ a 
